Question

When a certain circuit consisting of a constant emf $E$, an inductance $L$ and a resistance $R$ is closed, the current in it increases with time according to curve $1$. If one of the parameters $(E,L$ or $R)$ is changed, then the $i-t$ curve shift to the curve $2$. Which parameter is changed and how?

• A. $L$ is increased
• B. $L$ is decreased
• C. $R$ is increased
• D. $R$ is decreased

Answer 1

The correct option is A $L$ is increased

The steady state current flowing through the circuit is,

$i_o=\frac{E}{R}$

For both the curves, $i_o$ is the same.

Hence, $E$ and $R$ remains the same and therefore, $L$ is changed.


As time constant $\tau =\frac{L}{R}$ is increased, therefore, $L$ is increased.

Hence, $\left(A\right)$ is the correct option.